The present invention relates to the general field of medical gas insufflation devices, in particular those used in surgery. The present invention relates more particularly to monitoring the quantity of gas remaining in a pressurized vessel connected to a passive or active insufflation device, the vessel typically being a cylinder containing gas that may optionally be liquefied.
The purpose of such monitoring is to ensure that the cylinder is changed soon enough to avoid insufflation needing to be interrupted suddenly and in untimely manner while in use.
Such monitoring is thus essential to avoid untimely and harmful stopping of insufflation in the middle of surgery or of therapy. At present, the quantity of gas remaining is conventionally monitored by monitoring the pressure within the cylinder. Warnings are thus issued to indicate that the pressure has dropped below a warning threshold, e.g. 10 bars.
Nevertheless, cylinders of a variety of formats, and thus containing different quantities and kinds of gases for a given internal pressure, can all be connected to the insufflation device.
When using small-capacity cylinders, the warning corresponds approximately to the remaining volume being too small for performing or terminating surgery or therapy.
However with cylinders of greater capacity, cylinder-empty warnings are triggered by a pressure threshold even though there still remains enough gas to continue one or even more surgical interventions or sessions of therapy without risk, even though the generally-low warning pressure has been reached. Frequently, the quantity of gas that is not used could have served to perform one or more other surgical interventions or sessions of therapy. In contrast, with a small cylinder, the warning is given late and leaves little time to change the cylinder before insufflation ceases.